2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 179Get this manual
Cylinder body Checking the piston ring grooves
1Measure the piston ring groovesReplace the piston if out of specificationPiston ring side clearance: Top ring0.04-0.08 mm (0.002-0.003 in) Second ring (6): 0.03-0.07 mm (0.001-0.003 in) Oil ring0.05-0.19 mm (0.002-0.007 in)
Checking the piston pin boss bore
1Measure the piston pin boss boreReplace the piston if out of specification
S62Y5790
Piston ring groove: Top ring1.23-1.25 mm (0.048-0.049 in) Second ring (6): 1.52-1.54 mm (0.060-0.061 in) Oil ring2.51-2.53 mm (0.099-0.100 in)